1. Field of the Invention
This invention relates generally to fiber optic connections, and more particularly to a method and apparatus for tapping a fiber optic system.
2. Prior Art
In the field of fiber optics, light beams are used as communication carriers of coded information, either in digital or analog form. In order to use the information carried by the light, it is necessary to provide an optical tap to "read" or "sense" the information. One of the problems associated with tapping the light are losses of light at the tap. Various techniques for tapping are shown in U.S. Pat. No. 4,555,920 to Newton et al; U.S. Pat. No. 4,273,412 to Hillegoods; IBM Technical Disclosure Bulletin Vol 27, No. 18, June, 1984, pp. 543 to 546; and U.S. Pat. No. 4,165,496 to DiDomineco et al.
These techniques, involving fusing of fibers, and the use of various couplers, and other techniques involving half mirrors, all have several serious drawbacks. One of the most common drawbacks is the relatively high loss e.g. about 3 dB per connection, which greatly reduces the light transmitted past the tap. This is especially critical when there are several taps to be made, since at each tap, if the loss is great at each tap, the amount of light being transmitted on is reduced such that a condition is rapidly reached that the light power is so diminished that it is no longer usable as a communications carrier.